The present invention relates to a novel fulcrum cooperating with a generally conical spring of the Belleville type, and more particularly to a novel fulcrum contact surface for a Belleville spring.
Belleville springs have been in use generally for diaphragm spring clutch assemblies for automotive vehicles or similar devices wherein the spring is arranged in the assembly to effect a biasing force against a clutch pressure plate to frictionally engage a driven disc disposed between the pressure plate and an engine driven flywheel. Several design considerations are attendent to an acceptable and efficient spring for a clutch assembly, such as the stiffness of the spring to provide an adequate biasing force, the avoidance of the snap action tendency inherent in a dished diaphragm spring, and the rate variation inherent in the spring. The present invention aids in overcoming these various problems.
Among the objects of the present invention is the provision of a shaped fulcrum or load contact surface to cooperate with a Belleville type spring acting to compensate for the spring rate or load variation inherent in a Belleville spring and to greatly extend the range over which a substantially constant load or a substantially linear rate may be provided. A suitable application of a Belleville spring is shown in the recently issued Smirl U.S. Pat. No. 3,747,731 where it is desired to maintain a substantially constant load over an extended range of deflection for the spring. Other applications where these objectives are desirable include transmissions or other drive arrangements.
Another object of the present invention is the provision of a novel rate controlling fulcrum for a Belleville spring wherein the need for adjustments of the spring due to wear or tolerance stack-ups is minimized or substantially eliminated.
A further object of the present invention is the provision of a novel fulcrum for a Belleville type spring which will avoid the problems that might occur where the design of the spring itself is extended too close to its practical limits of deflection. Such problems could occur in the use of a Belleville spring in applications such as for the piston return springs of automatic transmissions.
Further objects are to provide a construction of maximum simplicity, efficiency, economy and ease of assembly and operation, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.